The patch titled
Subject: [PATCH] mm, vmalloc: fix high order __GFP_NOFAIL allocations
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
mm-vmalloc-fix-high-order-__gfp_nofail-allocations.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-vmalloc-fix-high-order-__gfp_nofail-allocations.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Michal Hocko <mhocko@xxxxxxxx>
Subject: [PATCH] mm, vmalloc: fix high order __GFP_NOFAIL allocations
Date: Mon, 6 Mar 2023 09:15:17 +0100
Gao Xiang has reported that the page allocator complains about high order
__GFP_NOFAIL request coming from the vmalloc core:
__alloc_pages+0x1cb/0x5b0 mm/page_alloc.c:5549
alloc_pages+0x1aa/0x270 mm/mempolicy.c:2286
vm_area_alloc_pages mm/vmalloc.c:2989 [inline]
__vmalloc_area_node mm/vmalloc.c:3057 [inline]
__vmalloc_node_range+0x978/0x13c0 mm/vmalloc.c:3227
kvmalloc_node+0x156/0x1a0 mm/util.c:606
kvmalloc include/linux/slab.h:737 [inline]
kvmalloc_array include/linux/slab.h:755 [inline]
kvcalloc include/linux/slab.h:760 [inline]
it seems that I have completely missed high order allocation backing
vmalloc areas case when implementing __GFP_NOFAIL support. This means
that [k]vmalloc at al. can allocate higher order allocations with
__GFP_NOFAIL which can trigger OOM killer for non-costly orders easily or
cause a lot of reclaim/compaction activity if those requests cannot be
satisfied.
Fix the issue by falling back to zero order allocations for __GFP_NOFAIL
requests if the high order request fails.
Link: https://lkml.kernel.org/r/ZAXynvdNqcI0f6Us@xxxxxxxxxxxxxx
Fixes: 9376130c390a ("mm/vmalloc: add support for __GFP_NOFAIL")
Reported-by: Gao Xiang <hsiangkao@xxxxxxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/20230305053035.1911-1-hsiangkao@xxxxxxxxxxxxxxxxx
Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@xxxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Baoquan He <bhe@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
--- a/mm/vmalloc.c~mm-vmalloc-fix-high-order-__gfp_nofail-allocations
+++ a/mm/vmalloc.c
@@ -2883,6 +2883,8 @@ vm_area_alloc_pages(gfp_t gfp, int nid,
unsigned int order, unsigned int nr_pages, struct page **pages)
{
unsigned int nr_allocated = 0;
+ gfp_t alloc_gfp = gfp;
+ bool nofail = false;
struct page *page;
int i;
@@ -2893,6 +2895,7 @@ vm_area_alloc_pages(gfp_t gfp, int nid,
* more permissive.
*/
if (!order) {
+ /* bulk allocator doesn't support nofail req. officially */
gfp_t bulk_gfp = gfp & ~__GFP_NOFAIL;
while (nr_allocated < nr_pages) {
@@ -2931,20 +2934,35 @@ vm_area_alloc_pages(gfp_t gfp, int nid,
if (nr != nr_pages_request)
break;
}
+ } else if (gfp & __GFP_NOFAIL) {
+ /*
+ * Higher order nofail allocations are really expensive and
+ * potentially dangerous (pre-mature OOM, disruptive reclaim
+ * and compaction etc.
+ */
+ alloc_gfp &= ~__GFP_NOFAIL;
+ nofail = true;
}
/* High-order pages or fallback path if "bulk" fails. */
-
while (nr_allocated < nr_pages) {
if (fatal_signal_pending(current))
break;
if (nid == NUMA_NO_NODE)
- page = alloc_pages(gfp, order);
+ page = alloc_pages(alloc_gfp, order);
else
- page = alloc_pages_node(nid, gfp, order);
- if (unlikely(!page))
- break;
+ page = alloc_pages_node(nid, alloc_gfp, order);
+ if (unlikely(!page)) {
+ if (!nofail)
+ break;
+
+ /* fall back to the zero order allocations */
+ alloc_gfp |= __GFP_NOFAIL;
+ order = 0;
+ continue;
+ }
+
/*
* Higher order allocations must be able to be treated as
* indepdenent small pages by callers (as they can with
_
Patches currently in -mm which might be from mhocko@xxxxxxxx are
mm-vmalloc-fix-high-order-__gfp_nofail-allocations.patch
